1. Field of the Invention
The present invention relates to a touch sensing apparatus and sensing signal processing method thereof, and more particularly, to a touch sensing apparatus and sensing signal processing method thereof for accelerating a sensing signal processing operation.
2. Description of the Prior Art
Along with the requirement of a friendly communication interface for a user to interact with an electronic device, a touch panel for controlling operations of the electronic device by directly touching the panel with fingers, instead of using a keyboard or a mouse, has gained popularity. In general, the touch panels are primarily classified into the resistive touch panels and the capacitive touch panels. The resistive touch panel positions a touched position according to related voltage drops changing in response to the touched position. The capacitive touch panel normally comprises a plurality of sensing capacitors, and the touched position can be positioned by analyzing the changing of capacitance of the sensing capacitor corresponding to the touched position.
FIG. 1 is a structural diagram schematically showing a prior-art touch sensing apparatus. As shown in FIG. 1, the touch sensing apparatus 100 comprises a first processing circuit 110, a second processing circuit 120, a sensing panel 130, a first transmission interface 140, a second transmission interface 150, a plurality of horizontal sensing lines 115, a plurality of vertical sensing lines 125, and a plurality of sensing units 135. The horizontal sensing lines 115, the vertical sensing lines 125 and the sensing units 135 are disposed on the sensing panel 130. Each sensing unit 135 is utilized for outputting one horizontal sensing signal and one vertical sensing signal responsive to touch events. Each horizontal sensing signal is forwarded to the first processing circuit 110 via one corresponding horizontal sensing line 115. Each vertical sensing signal is forwarded to the second processing circuit 120 via one corresponding vertical sensing line 125. The vertical sensing signals are transmitted to the first processing circuit 110 via the first transmission interface 140 after undergoing a preliminary signal operation performed by the second processing circuit 120. The first processing circuit 110 generates a touch coordinate signal by analyzing the horizontal sensing signals and the vertical sensing signals. The second transmission interface 150 is employed to transmit the touch coordinate signal to a host 180 so that the host 180 is able to control image-related operations on a display panel 190.
FIG. 2 is a timing diagram schematically showing the scanning times regarding the sensing signal processing operation of the touch sensing apparatus in FIG. 1, having time along the abscissa. The scanning times in FIG. 2, from top to bottom, are the scanning time of the first processing circuit and the scanning time of the second processing circuit. As shown in FIG. 2, when the touch sensing apparatus 100 performs the sensing signal processing operation, the first processing circuit 110 is enabled for starting the scanning process regarding the horizontal sensing lines 115 during the first preliminary scanning buffer time Tb1. After the first preliminary scanning buffer time Tb1, the first processing circuit 110 performs the scanning process over the horizontal sensing lines 115 for fetching the horizontal sensing signals during the horizontal scanning time Tx.
After the horizontal scanning time Tx, the second processing circuit 120 is enabled for starting the scanning process regarding the vertical sensing lines 125 during the second preliminary scanning buffer time Tb2. After the second preliminary scanning buffer time Tb2, the second processing circuit 120 performs the scanning process over the vertical sensing lines 125 for fetching the vertical sensing signals during the vertical scanning time Ty. After the vertical scanning time Ty, the first processing circuit 110 performs an analysis on the horizontal sensing signals and the vertical sensing signals for generating a touch coordinate signal during the signal processing time Tp. The aforementioned sensing signal processing operation from the first preliminary scanning buffer time Tb1 to the signal processing time Tp is repeated periodically for continuously updating the touch coordinate signal.
It is noted that the second processing circuit 120 is idle while the first processing circuit 110 is scanning over the horizontal sensing lines 115, and the first processing circuit 110 is idle while the second processing circuit 120 is scanning over the vertical sensing lines 125. Furthermore, after the scanning process of the first processing circuit 110 is finished, the second preliminary scanning buffer time Tb2 is required to enable the second processing circuit 120 for starting the scanning process regarding the vertical sensing lines 125. Accordingly, regarding the low-efficiency sensing signal processing operation of the prior-art touch sensing apparatus, the operating speed of the scanning processes for fetching sensing signals is hard to boost in that the scanning times are difficult to be shortened. That is, based on the low-speed sensing signal processing operation, the touch coordinate signal cannot be updated in a real time, and parts of the touch data will be lost. In particular, while tracking a touch trajectory over a fast-changing touch event, trace errors are likely to occur due to the loss of parts of the touch data.